Biomedical subjects

Yoshihiro Minamiya

Publications and source records attributed to Yoshihiro Minamiya.

29 records · Page 2Linked to original sources

PubMed2004

Methylprednisolone-induced expression of mitochondrial heat shock protein 60 protects mitochondrial membrane potential in the hypoxic rat liver.

This study investigated the contribution made by mitochondrial heat shock protein (hsp) 60 to methylprednisolone-mediated protection against mitochondrial membrane depolarization under hypoxic conditions. A low-flow hypoxia model was generated in isolated male, fasted, pathogen-free Sprague-Dawley rat livers by reducing perfusate inflow pressure from 10 to 2.5 cm H2O for 2 h. The effects of methylprednisolone on mitochondrial membrane potential and expression of mitochondrial hsp 60 protein and mRNA were determined. We measured mitochondrial membrane potential by imaging rhodamine 123 fluorescence. Induction of mitochondrial hsp 60 was detected using two different anti-hsp 60 antibodies: one against the N-terminal signal sequence, which reacted exclusively with cytoplasmic hsp 60, and one against a different epitope, which reacted with cytoplasmic and mitochondrial hsp 60. In addition, the distribution of hsp 60 mRNA was examined using in situ hybridization. We found that under hypoxic conditions, there was a significant decline in mitochondrial membrane potential that was accompanied by a mild decline in the level of mitochondrial hsp 60, and that cytosolic hsp 60 was translocated into mitochondria. Pretreatment with methylprednisolone inhibited the declines in mitochondrial membrane potential and hsp 60 protein, as well as the translocation of cytosolic hsp 60. This raises the possibility that one way in which methylprednisolone protects the mitochondrial membrane potential under hypoxic conditions is to induce expression of mitochondrial hsp 60.

Animals↗

PubMed2003

Hydrogen peroxide-dependent declines in Bcl-2 induces apoptosis in hypoxic liver.

BACKGROUND: Low-flow hypoxia induces xanthine oxidase-dependent hydrogen peroxide production by hepatocytes in the midzone of blood-perfused rat livers and apoptosis in sinusoidal endothelial cells (SECs). As Bcl-2 is a potent inhibitor of apoptotic cell death and is localized mainly in the inner mitochondrial membrane and crista, the purpose of this study was to determine whether cell-specific changes in mitochondrial Bcl-2 levels could account for the hypoxia-induced apoptosis in SECs. MATERIALS AND METHODS: A low-flow hypoxia model was generated in isolated rat livers by reducing perfusate inflow pressure from 10 to 2.5 cmH2O for 2 h. Apoptosis was then evaluated using the TdT-mediated dUTP-digoxigenin nick end-labeling (TUNEL) method. Mitochondrial Bcl-2 protein levels were determined in hepatocytes and SECs using cryosectioning immunogold labeling electron microscopy.Results. TUNEL-positive nonparenchymal cells, identified as SECs, were observed predominantly in the midzone of low-flow hypoxic rat livers, whereas few parenchymal cells were stained. Mitochondrial Bcl-2 levels were higher in SECs than in hepatocytes under control conditions, but they declined significantly during hypoxia, though no morphological signs of apoptosis were apparent. In hepatocytes, by contrast, Bcl-2 levels were unaffected by hypoxia. Pretreatment with a specific xanthine oxidase inhibitor, sodium (-)-8-(3-methoxy-4-phenylsulfinylphenyl) pyrazolo [1,5-a]-1,3,5-triazine-4-olate monohydrate, which blocks production of hydrogen peroxide, also blocked both the hypoxia-induced apoptosis and the decline in mitochondrial Bcl-2 in SECs. CONCLUSION: Hydrogen peroxide-dependent declines in Bcl-2 induce apoptosis in SECs in the hypoxic rat liver.

Animals↗

PubMed2003

A novel method for sentinel lymph node mapping using magnetite in patients with non-small cell lung cancer.

OBJECTIVE: The detection rate of sentinel lymph nodes in patients with non-small cell lung cancer using isosulfan blue dye is too low for clinical use. Although exposure to radioactivity is reportedly minimal, special procedures are nonetheless required when a radioactive isotope is used as a tracer. Therefore, to eliminate the need for a radioactive tracer and to obtain a better detection rate than is obtained with isosulfan blue dye, we have developed a novel method that employs magnetite as the tracer. The aim of the present study was to test the feasibility of this technique. METHODS: The tracer employed was ferumoxides, a colloidal superparamagnetic iron oxide of nonstoichiometric magnetite. Thirty-eight non-small cell lung cancer patients participated in the study; each received 5 mL of ferumoxides, injected around the tumor intraoperatively. Fifteen minutes after injection, lung resection and lymph node dissection were carried out. The magnetic force within the lymph nodes was measured using a highly sensitive handheld magnetometer ex vivo. All lymph nodes were also subjected to conventional histological analysis. RESULTS: The rate of detection of sentinel lymph nodes was 81.6% (31/38). The accuracy, sensitivity, and false-negative rates were 96.8% (30/31), 85.7% (6/7), and 14.3% (1/7), respectively. CONCLUSION: Intraoperative sentinel lymph node mapping using ferumoxides and a highly sensitive magnetometer is a safe, accurate, and sensitive way to detect sentinel lymph nodes in non-small cell lung cancer patients.

Adult↗

PubMed2003

Methylprednisolone inhibits low-flow hypoxia-induced mitochondrial dysfunction in isolated perfused rat liver.

OBJECTIVE: To investigate the mechanism by which methylprednisolone protects the liver from hypoxia-induced injury. DESIGN: Prospective control study using the isolated rat liver. SETTING: Animal research facility. SUBJECTS: Male, fasted, pathogen-free Sprague-Dawley rats. INTERVENTIONS: Low-flow hypoxia was produced by reducing afferent perfusate pressure from 10 to 2.5 cm H(2)O; isolated livers were portally perfused for 2 hrs. MEASUREMENTS AND MAIN RESULTS: We measured mitochondrial membrane potential and hydrogen peroxide production by imaging rhodamine 123 and 2'-7'-dichlorofluorescein fluorescence, respectively. Leakage of mitochondrial enzymes was also monitored by assaying mitochondrial aspartate aminotransferase activity in the outflow perfusate, and the radical-scavenging effect of methylprednisolone was assessed by measuring luminol-dependent hydrogen peroxide chemiluminescence. Apoptosis in liver cells was determined by using terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling. Rhodamine 123 fluorescence was significantly diminished in the hypoxic liver, especially in the region of the terminal hepatic venules, which is indicative of membrane depolarization in the mitochondria in those areas. Hypoxia-induced mitochondrial dysfunction was indicated by leakage of aspartate aminotransferase into the outflow perfusate, and increased 2'-7'-dichlorofluorescein fluorescence indicated increased hydrogen peroxide levels, particularly in the midzone. Pretreatment with 30, 10, or 3 mg/kg of methylprednisolone inhibited the hypoxia-induced mitochondrial membrane depolarization and enzyme leakage, although hydrogen peroxide levels and apoptosis in sinusoidal endothelial cells were unaffected. CONCLUSIONS: Methylprednisolone does not protect the liver from hypoxia-induced injury by suppressing hydrogen peroxide production. Instead, the beneficial effect of methylprednisolone seems to be related to its ability to protect against mitochondrial membrane depolarization under hypoxic conditions.

Animals↗

PubMed2003

[A novel method for sentinel lymph node mapping using magnetite].

The detection rate of sentinel lymph nodes using isosulfan blue dye is too low for clinical use. Although exposure to radioactivity is reportedly minimal, special procedures are nonetheless required when a radioactive isotope is used as a tracer. Therefore, to eliminate the need for a radioactive tracer and to obtain a better detection rate than is currently obtained with isosulfan blue dye, we have developed a novel method that employs magnetite as the tracer. The tracer employed is ferumoxides, a colloidal superparamagnetic iron oxide of non-stoichiometric magnetite. The magnetic force within the lymph nodes was measured using a highly sensitive hand-held magnetometer ex vivo. The rate of detection of sentinel lymph nodes was 82% in non-small cell lung cancer. Intraoperative sentinel lymph node mapping using ferumoxides and a highly sensitive magnetometer is a safe, accurate, and sensitive way to detect sentinel lymph nodes. To detect sentinel lymph nodes in vivo, the magnetometer should be sterilized and the sensitivity of the magnetometer should be higher than that we used. Therefore now we are developing a more sensitive and sterilizable magnetometer.

Contrast Media↗

PubMed2002

Signaling pathway for radiation-induced apoptosis in the lymphoblasts from neuronopathic (type A) and non-neuronopathic (type B) forms of Niemann-Pick disease.

Deficient activity of human lysosomal hydrolase, acid sphingomyelinase (ASM), results in the neuronopathic (type A) and non-neuronopathic (type B) forms of Niemann-Pick disease (NPD). A deficiency of ASM is known to deprive lymphoblasts of their response to apoptotic induction by X-ray irradiation. To elucidate the genetic heterogeneity of apoptotic induction in NPD cells, we investigated radiation-induced apoptosis of lymphoblasts in patients with type A (genotype: IVS3-2A-G/IVS3-2A-G) and type B (genotype: S436R/S436R) NPD. Epstein-Barr virus (EBV)-transformed lymphoblasts established from a patient with type A NPD, a patient with type B NPD and a normal control were irradiated with 20 Gy and incubated for 24 h. The cells were harvested and the morphological features of apoptosis were observed with DNA-specific fluorochrome bis-benzimide. Exposure of lymphoblasts to 20 Gy of radiation resulted in 25-30% apoptosis of total cells in normal lymphoblasts, 8-9% apoptosis in type A NPD and 20-27% apoptosis in type B NPD. The radiation-induced apoptotic response in the lymphoblasts of type A NPD was significantly different from that of the normal lymphoblasts (P<0.0005). On the other hand, the radiation-induced apoptotic response in type B NPD was not markedly different from that in normal lymphoblasts (P=0.624). In the patient with type B NPD, the signaling pathway for radiation-induced apoptosis was preserved in lymphoblasts, which suggests that the extent of cell signaling system disturbance due to ASM deficiency may be related to the phenotypes in types A and B NPD.

Amino Acid Substitution↗

PubMed2002

Indication for preoperative localization of small peripheral pulmonary nodules in thoracoscopic surgery.

OBJECTIVE: Widespread clinical use of helical computed tomography has improved the detection rate for small peripheral pulmonary nodules. As a result, use of thoracoscopic surgery to confirm the diagnosis of small peripheral pulmonary nodules has become more important than ever before. However, if small peripheral pulmonary nodules are too small or located too deeply to detect thoracoscopically, it is necessary to mark the small peripheral pulmonary nodules preoperatively. The purpose of this study was to determine indications for preoperative hookwire marking in thoracoscopic resection of small peripheral pulmonary nodules. METHODS: A total of 120 patients underwent thoracoscopic pulmonary resection in our institute from 1999 to 2001. Small peripheral pulmonary nodules were marked preoperatively in 61 of these patients by means of percutaneous placement of a hookwire under computed tomographic guidance. The hookwire-marked small peripheral pulmonary nodules either were smaller than 10 mm or were located more than 10 mm below the pleural surface. RESULTS: Although 9 of the hookwire-marked small peripheral pulmonary nodules were easily identified during thoracoscopy, the other 52 small peripheral pulmonary nodules could not have been identified during thoracoscopy without the hookwire marking. Of the 59 small peripheral pulmonary nodules that were not hookwire marked, 7 required conversion to thoracotomy to locate the nodules. Small peripheral pulmonary nodules from both groups were examined and assigned to either an undetectable or detectable group. Discriminant function analysis indicated that a linear function (ie, depth = 0.836 x size - 2.811) could be used to differentiate between undetectable and detectable small peripheral pulmonary nodules, and preoperative hookwire marking for small peripheral pulmonary nodules should be considered for nodules in the region above those. CONCLUSION: The results suggest that this formula might serve as an indication for preoperative marking of small peripheral pulmonary nodules in thoracoscopic resection.

Female↗

PubMed2002

Nafamostat mesilate attenuates radical formation in the rat lung infused with endotoxin.

We previously reported direct evidence of respiratory bursting by neutrophils in the pulmonary circulation of endotoxin-infused rats. To evaluate the effect of the protease inhibitor nafamostat mesilate (NM) on leukocyte-mediated radical formation in the pulmonary circulation of rats infused with endotoxin, we observed and measured the number of sticking leukocytes and quantified radical production in the pulmonary circulation of endotoxin-infused rats by means of a fluorescent imaging technique. Plasma C3a (desArg) was also measured using an enzyme-linked immunosorbent assay. Three groups (n = 5) of rats were infused with 4.5 mg/kg/h endotoxin (Et group), 50 microg/kg/h NM + endotoxin (NM group), or physiological saline (Ct group) for 2 h. The number of the leukocytes adhering within pulmonary capillaries, oxygen radical production in the rat pulmonary circulation, and plasma C3a (desArg) were all lower in the NM group than in the Et group. The leukocytes producing oxygen radicals were confirmed to be neutrophils by electron microscopic analysis of cerium deposition. We conclude that NM attenuates plasma C3a formation, neutrophil adherence to pulmonary capillaries, and their production of oxygen radical in rats infused with endotoxin.

Animals↗

PubMed2002

[A case of long-term remission with salvage surgeries for chemotherapy-resistant germ cell tumor of testis].

A patient with non-seminomatous germ cell tumor of testis underwent operations for metastases in the lung and mediastinum three times, when the serum AFP level remained remarkably high despite of intensive chemotherapy, and has been disease-free for three years after the last treatment. Our experience illustrates that the salvage surgery even under high serum marker levels may provide a beneficial outcome for selected cases of chemotherapy-resistant germ cell tumors.

Adult↗

PubMed2002

Endothelial Rho and Rho kinase regulate neutrophil migration via endothelial myosin light chain phosphorylation.

The transendothelial migration of neutrophils is a critical step in acute inflammation, which we previously showed to be regulated by endothelial myosin light chain (MLC) kinase. Recent studies suggest that Rho and Rho kinase are also key mediators of MLC phosphorylation, but their roles in neutrophil migration have not been investigated. In the present study, a transwell chamber migration assay system incorporating endothelial monolayer was used to examine the numbers of migrating neutrophils, endothelial F-actin and myosin II rearrangement, and endothelial MLC phosphorylation at selected times during the neutrophil migration in vitro. The results showed that pretreating endothelial cells with C3 (Rho inhibitor) or Y-27632 (Rho kinase inhibitor) significantly diminished neutrophil migration, actin polymerization, myosin II filament formation, and MLC phosphorylation normally associated with the migration. These data suggest that endothelial Rho and Rho kinase regulate transendothelial neutrophil migration by modulating the cytoskeletal events that mediate such migration.

Actins↗

PubMedDate not supplied

Clinical presentation of pulmonary edema following esophagectomy on chest radiograph.

BACKGROUND/AIMS: To determine whether the clinical presentation of pulmonary edema following esophagectomy can be objectively determined by changes in X-ray density in the lung field on chest radiography. METHODOLOGY: Sixteen patients who underwent esophagectomy for thoracic esophageal cancer and five patients who underwent less radical surgery at Akita University Hospital between July 2000 and March 2001 were recruited to the thoracic esophageal cancer and control groups, respectively. Chest radiography was carried out using five aluminum disks (15, 20, 25, 30 and 35 mm thickness) placed in upper right corner of the film and X-ray density for the disks and chest lung field was measured using a densitometer until POD 7. RESULTS: In the thoracic esophageal cancer group, X-ray density in the lung field, body weight, and respiratory index increased significantly in the immediate postoperative period. The X-ray density in the lung field peaked on POD 2, and remained constant to POD 6. Correlations were found among changes in X-ray density in the lung field, body weight, and respiratory index. CONCLUSIONS: The measurement of X-ray density on a chest radiograph is useful for prediction as well as early management of patients with pulmonary edema following esophagectomy for thoracic esophageal cancer.

Aged↗